Device and method for the geometric determination of electrical dipole densities on the cardiac wall

ABSTRACT

Disclosed are devices ( 100 ), systems ( 500 ), and methods for determining the dipole densities on heart walls. In particular, a triangularization of the heart wall is performed in which the dipole density of each of multiple regions correlate to the potential measured at various located within the associated chamber of the heart. To create a database of dipole densities, mapping information recorded by multiple electrodes ( 316 ) located on one or more catheters ( 310 ) and anatomical information is used. In addition, skin electrodes may be implemented. Additionally, one or more ultrasound elements ( 340 ) are provided, such as on a clamp assembly or integral to a mapping electrode, to produce real time images of device components and surrounding structures.

FIELD OF THE INVENTION

The present invention relates generally to the localization andtreatment of cardiac arrhythmias, and more particularly to devices andmethods for real time, non-contact imaging and distance measurementsusing ultrasound for dipole density mapping, as well as methods fordiagnosing tissue health.

BACKGROUND OF THE INVENTION

Systems used to localize the origin of cardiac arrhythmias measurepotentials (e.g. in millivolts) in the cardiac chambers and localizethem on a three dimensional representation of the cardiac chamber wall.The measurement of the electrical activity present on the cardiac wallsis called mapping. For this purpose, a multiple electrode mappingcatheter may be positioned within the heart such that multiplepotentials can be simultaneously measured at different locations on thewall of the cardiac chamber without having direct wall contact(non-contact mapping). The cardiac chamber is visualized as a threedimensional structure, either directly by moving one or more mappingelectrodes within the corresponding heart chamber or by importing ananatomical geometry of the cardiac chamber from an imaging device (e.g.Computed Tomography, MRI, or ultrasound). The electrical activity withinthe heart can be measured with the multi-electrode mapping catheter,which may be able to simultaneously measure potentials at differentpoints in three dimensional space. In the current systems, the measuredpotentials from the non-contact multi-electrode mapping catheter do notdirectly correspond to the electrical activity on the cardiac wall asmeasured with an electrode with direct wall contact (contact mapping).The measured potentials of the non-contact mapping system have to beconverted with computer programs and extrapolated into virtualelectrograms projected on the heart chamber of the mapping system.

U.S. Pat. No. 5,297,549 (Beatty, et al.) discloses a method ofgenerating a three-dimensional map of electrical activity in a heartchamber as well as a two-dimensional map of the electrical activitywithin the endocardial surface. Beatty generates the information via anarray of electrodes placed in a heart chamber utilizing impedanceplethysmography, while one electrode serves as a reference.

The current conversion methods suffer various instabilities, and furtherprocessing, termed regularization, must be applied to maintainstability. Regularization decreases spatial resolution. Anotherlimitation of the current methods is that the provided potentialsrepresent only the mean electrical activity summed across a large regionof tissue, with cells consisting of membranes separating electricaldipoles.

Since the localization of cardiac arrhythmias by the use of potentialsis imprecise, the successful treatment of cardiac arrhythmias has beendifficult and has demonstrated limited success and reliability. Thereis, therefore, a need for improved methods of localizing cardiacarrhythmias.

SUMMARY

The present invention discloses devices and methods for real time,non-contact imaging and distance measurements using ultrasound fordipole density mapping, as well as methods for diagnosing tissue health.In one aspect, the present invention includes a device comprising one ormore catheters, each catheter comprising a shaft. The shaft may includea lumen and may be steerable. The shaft may include, typically near itsdistal end, one or more components selected from group consisting of:electrodes, such as electrodes configured to record electrical activityof tissue; transducers such as ultrasound transducers; sensors, such asultrasound sensors; ultrasound crystals configured to both transmit andsense ultrasound waves; and combinations of these. The device isconstructed and arranged to produce continuous, real-time images of apatient's tissue, as well as information related to electrical activitypresent in the tissue. For example, a user, such as a clinician mayimage a patient's cardiac chamber, including the cardiac walls. Thedevice is also capable of providing tissue information, for example,tissue movement and tissue thickness. Additionally, the device isconfigured to produce distance measurements by analyzing at least one ofthe sensors recorded angles or frequency changes. Non-limiting examplesof distance measurements include: distance between the multipleelectrodes and the wall of the cardiac chamber and distance between themultiple electrodes and the transducer and/or sensor. The device may beconfigured to provide a tissue diagnostic through an analysis of bothtissue motion information and cell electrical signals. The cellelectrical signals may be recorded by the multiple electrodes, whiletissue motion information may be gathered by the multiple electrodesand/or the sensor. The device is configured to provide exact foci andconduction-gap position information, such that ablation is performedwith an increased level of precision. Small conduction paths, including“gaps” in a line, are equally relevant as foci. The device may includean ablation catheter, such as an ablation catheter that can be preciselydelivered through an open lumen of a second device catheter, or througha sheath.

In some embodiments, the device may include a catheter which is furtherconfigured as a delivery sheath. For example, a first catheter maycomprise a lumen, such that a separate ablation catheter may beslidingly received by the first catheter. Additionally, a single sheathmay be provided to allow the first catheter and the ablation catheter topass there though. This construction would eliminate the need formultiple sheath devices.

In some embodiments, one or more catheters of the device may besteerable. For example, a user may determine the ablation site viareal-time tissue analysis and imaging, and subsequently a catheter maybe steered to the desired location. Steering of one or more cathetersmay be achieved via cables, such as cables which may be housed in alumen of a delivery sheath.

The device comprises a transducer, preferably an ultrasound transducerconfigured to produce sound waves, typically at a frequency between 5and 18 MHz. The sound waves may be at a constant rate or provided in apulsed manner. The device may comprise multiple transducers. One or moretransducers may be positioned on one or more catheters of the device,such as on or near a distal portion of a catheter. One or moretransducers may be further configured as sensors, such as ultrasoundcrystals that both record and emit sound waves.

The device comprises a sensor, preferably an ultrasound sensorconfigured to receive the sound waves produced by the ultrasoundtransducer. The device may comprise multiple sensors. One or moresensors may be positioned on one or more catheters of the device, suchas on or near a distal portion of a catheter. One or more sensors may befurther configured as transducers, such as ultrasound crystals that bothrecord and emit sound waves.

The sensors, transducers, or combination sensor/transducers may bepositioned on the device in various locations including but not limitedto: attached to the shaft of the catheter; housed within the shaft ofthe catheter, for example, the sensor and/or transducer may be slidinglyreceived by the shaft; at the geometric center of each of the multipleelectrodes; proximate to at least one of the multiple electrodes;mounted to a multiple arm assembly; and combinations of these. Thedevice may include one or more electrodes configured to recordelectrical activity in the tissue of cells. Various ratios of electrodesto sensors, transducers, or combination sensor/transducers may beincluded. In one embodiment, a ratio of two electrodes to one ultrasoundcrystal is provided, such as a single component with one ultrasoundcrystal and an electrode positioned at each end of the crystal. Inanother embodiment, a ratio of five electrodes to two sensor/transducersis provided, such as a catheter shaft including two assemblies and asingle electrode. Each assembly includes an ultrasound crystal with anelectrode positioned at each end.

The transducer and/or the sensor may be rotated, which may include apartial rotation or a full 360° rotation. Alternatively or additionally,the sensor and/or transducer may be translated along a linear axis. Inone embodiment, the sensor and/or transducer comprise a piezoelectricfilm. For example, a wire may be electrically connected to a firstelectrode where a portion of the wire comprises a piezoelectric film.Alternatively, the sensor and/or transducer may comprise a piezoelectriccable.

In some embodiments, the sensor and transducer may comprise a singlecomponent, for example, a single crystal. Alternatively, the sensorand/or transducer may comprise an array of components, for example, acircumferential array of ultrasound crystals. Each of the ultrasoundcrystals may be attached to one or more electrodes configured to recordelectrical activity of living cells.

The device further comprises a first receiver that receives mappinginformation from multiple electrodes included in one or more cathetersconfigured to perform mapping of cellular electrical activity, such aselectrocardiogram activity. The electrodes are placed in a cardiacchamber of the patient's heart. The device further includes a secondreceiver that receives anatomical information. The anatomicalinformation may be a generic heart model, or more preferably tissuecontour and other anatomical information recorded from the patient's ownheart. A dipole density module determines the database of dipoledensities, in the table form d(y), where y represents thethree-dimensional location on the heart tissue including that particulardipole density. The potential at various other locations x, within acardiac chamber and termed V(x), are recorded by the multipleelectrodes. Solid angle {acute over (ω)}(x,y) represents the solid anglefor a triangle projection between location x (electrode location inchamber) and y (triangle location on chamber wall). The dipole densitymodule determines the dipole density for individual triangle shapedprojections onto the cardiac chamber wall based on the following: eachtriangle projection at location y contributes {acute over (ω)}(x,y)times the dipole density d(y) to the potential V(x) at the point x.

In a preferred embodiment, the device comprises a software program,e.g., such as a software program loaded onto a personal computer; an ECGsystem; a cardiac tissue ablation system and/or an imaging system. Thenumber of triangles determined by the dipole density module issufficiently large (triangle area small enough) such that the dipoledensity for each triangle projection is relatively constant. Typically1000 or more triangles are used in the calculations, such as acalculation based on a standard sized Left or Right Atrium. Largernumbers of triangles are used for larger sized chambers.

In another preferred embodiment, the patient is being diagnosed and/ortreated for a heart condition, such as an arrhythmia. The electrodes areincluded at the distal end of one or more mapping catheters and areplaced into a chamber of the patient's heart to record potentials. Animaging instrument, such as an instrument that provides a generic modelof a heart, or an instrument which provides an anatomical model of thepatient's heart, delivers the anatomical information to the secondreceiver. In one embodiment, the imaging instrument is one or more of:Computed Tomography; MRI; ultrasound; and an ECG system with mappingcatheter. Alternatively or additionally, an imaging instrument may beintegrated into the device, such as an ultrasound unit configured toproduce image and distance information from signals received from one ormore ultrasound sensors.

In another preferred embodiment, the dipole density module implements analgorithm configured to assist in the creation of the database of dipoledensities. The algorithm may be a progressive algorithm configured to bemodified or refined to improve spatial and/or time resolution of thedatabase. The dipole density module may determine a map of dipoledensities at corresponding time intervals. A synthesis of mapsrepresents a cascade of activation sequences of each corresponding heartbeat.

In another preferred embodiment, the device includes a third receiver.The third receiver collects mapping information from one or more skinelectrodes. The dipole density module uses the skin electrode signals tocalculate or recalculate the database of dipole densities, usingequations listed herebelow.

According to another aspect of the invention, a system for creating adatabase of dipole densities at the surface of one or more cardiacchambers of a patient's heart is provided. In addition to the device ofthe present invention, the system includes one or more multipleelectrode catheters; an ablation device; at least one surface or skinelectrode; a transducer; and a sensor. A separate imaging instrument maybe included in the system. In a preferred embodiment, the mappingcatheter is also used for ablating tissue identified by the database ofdipole densities and positioned in the heart chamber using the real-timeimaging. The system includes a monitor to display the real-time imageand dipole density information, such as information displayed inrelative geometry to the chamber of the patient's heart.

According to another aspect of the invention, a method of creating adatabase of dipole densities at the surface of one or more cardiacchambers of a patient's heart is provided. The method can be used todiagnose and/or treat complex cardiac arrhythmia disease. In a typicalconfiguration, complex electrograms are identified, such as a method inwhich three or more complex electrograms are identified. In a preferredembodiment, the method is used to diagnose and/or treat AtrialFibrillation (AF), Ventricular Tachycardia (VT), Atrial Flutter andtissue scarring, such as tissue scarring caused by an intra-cardiacdefibrillator (ICD). In another preferred embodiment, the method is usedto detect ventricular ischemia and/or quantify myocardial function. Themethod includes placing an array of multiple electrodes within a chamberof the patient's heart to measure potentials and calculating thedistance or movement information by analyzing signals received from asound sensor. The array of multiple electrodes may or may not berepositioned to determine dipole densities.

In another preferred embodiment, the method further includes placing oneor more skin electrodes. The information recorded by the skin electrodesis used to determine the database of dipole densities. In yet anotherembodiment, the method further comprises calculating tissue thicknessinformation.

According to another aspect of the invention, a medical method forobtaining electrical and anatomical information related to a patient'scardiac chamber(s) is disclosed. In a first step, a user may insert adevice into a delivery system. The device may be any device describedhereabove. In a next step, the user may advance the device through thedelivery system and into a heart chamber. In a next step the deviceand/or delivery system may be steered such that the distal end of thedevice is positioned approximately in the geometric center of the heartchamber. Once the device is positioned within the heart chamber,measurements may be obtained and analyzed consistent with measurementsand methods disclosed herein.

According to another aspect of the invention, a method for diagnosingtissue is disclosed. The preferred method comprises placing a distal endof an electrode catheter into one or more cardiac chambers of a patient,where the electrode catheter comprises at least one electrode and atleast one ultrasound element. In a next step, anatomical information,such as tissue movement, may be determined via the at least oneultrasound element. In a next step, the electrical charge of a tissuemay be determined via the at least one electrode. Lastly, by analyzingtissue movement and electrical charge information, tissue health may bedetermined.

For example, electrical information indicative of adequate electricalactivity and anatomical information indicative of adequate tissue motioncorrelates to presence of healthy tissue. Additionally, electricalinformation indicative of adequate electrical activity and anatomicalinformation indicative of inadequate tissue motion correlates topresence of at least one of ischemic tissue or hibernating tissue.Conversely, electrical information indicative of inadequate electricalactivity and anatomical information indicative of inadequate tissuemotion correlates to presence of scar tissue. Additionally, electricalinformation indicative of inadequate electrical activity and anatomicalinformation indicative of inadequate tissue motion correlates topresence of a complete ablation, such as an ablation performed in acardiac ablation performed to treat a cardiac arrhythmia. In someembodiments, the complete ablation comprises a transmural ablation.

More specifically, the following four cases may exist:

-   -   Case 1: Electrical and anatomical are adequate—Tissue is        healthy,    -   Case 2: Electrical is adequate and anatomical is        inadequate—Tissue is compromised,    -   Case 3: Electrical is inadequate and anatomical is        adequate—Tissue is compromised, and    -   Case 4: Electrical and anatomical are both inadequate—Tissue        necrosis.

The actual threshold for determining adequacy of electrical function ofany one area of the heart is dependent upon many factors, including thedegree of coordination of the activation pattern and the mass of thecells being activated. Additionally, this threshold will be differentfor each chamber of the heart as well as from smaller to largerpatients. For example, a threshold of 0.5 mV may be appropriate, whereinan electrical potential smaller that 0.5 mV may be indicative ofinadequate electrical function and an electrical potential at or largerthan 0.5 mV may be indicative of adequate electrical function.

Also included in the tissue diagnostic, a clinician may assess theelectrical integrity of the cardiac cells. For example, the functionalstatus of the cardiac cells may be assessed.

In one embodiment, the electrical information comprises dipole densityinformation. Additionally or alternatively, the electrical informationmay comprise at least one of repolarization or speed of wave-frontpropagation.

The method may further comprise ablating the cardiac tissue based uponthe tissue diagnosis. For example, the anatomical information comprisestissue thickness information and at least one of the ablation energy orthe time period is adjusted based on the tissue thickness information. Aclinician may assess the tissue during and post ablation to assesschanges in the tissue due to the application of the ablation energy. Forexample, the clinician may also use information received form one ormore ultrasound sensors in combination with dipole density mappinginformation received from one or more electrodes to assess the adequacyof tissue ablation, such as to improve long-term patient outcomes.

In accordance with an aspect of the present invention, provided is adevice for creating a database of dipole densities d(y) and distancemeasurements at the surface of one or more cardiac chambers of apatient. The device comprise: multiple electrodes located on one or morecatheters; a transducer constructed and arranged to emit sound waves;and a sensor constructed and arranged to receive reflections of thesound waves.

In various embodiments, the transducer can comprise the sensor.

In various embodiments, the transducer can further comprise at least oneof the multiple electrodes.

In various embodiments, the device can be constructed and arranged toproduce a real time image.

In various embodiments, the device can be constructed and arranged toproduce continuous images.

In various embodiments, the device can be constructed and arranged toproduce images of the patient's tissue.

In various embodiments, the image can comprise an image of the one ormore cardiac chambers.

In various embodiments, the image can comprises an image of a wall ofthe one or more cardiac chambers.

In various embodiments, the image can comprise an image of tissueproximate at least one of the multiple electrodes.

In various embodiments, image can comprise an image of at least one ofthe multiple electrodes.

In various embodiments, the device can be constructed and arranged toprovide motion information of the patient's tissue.

In various embodiments, the motion information can comprise cardiac wallmotion information.

In various embodiments, the device is constructed and arranged toprovide thickness information of the patient's tissue.

In various embodiments, the thickness information can be cardiac wallthickness information.

In various embodiments, the device can be constructed and arranged toproduce an image of at least one of the multiple electrodes.

In various embodiments, the device can be constructed and arranged tofurther produce an image of tissue proximate at least one of themultiple electrodes.

In various embodiments, the device can be constructed and arranged tofurther produce an image of the one or more cardiac chambers.

In various embodiments, the device can be constructed and arranged toproduce a distance measurement.

In various embodiments, the distance measurement can comprise thedistance between at least one of the multiple electrodes and a wall of acardiac chamber.

In various embodiments, the distance measurement can comprise thedistance between at least one of the multiple electrodes and at leastone of the transducer or the sensor.

In various embodiments, the distance measurement can comprise thedistance between a wall of a cardiac chamber and at least one of thetransducer or the sensor.

In various embodiments, the device can be constructed and arranged toproduce the distance measurement by analyzing at least one of sensorrecorded angle or frequency changes.

In various embodiments, the device can be constructed and arranged todetermine the position of at least one of the multiple electrodes withina cardiac chamber.

In various embodiments, the device can be constructed and arranged todetermine the position of at least two of the multiple electrodes withinthe cardiac chamber.

In various embodiments, the device can be constructed and arranged tocombine distance information received from the multiple electrodes withinformation received from the sensor.

In various embodiments, the device can be constructed and arranged toprovide tissue diagnostic information by analyzing both tissue motioninformation and cell electrical signals.

In various embodiments, the cell electrical signals can be recorded bythe multiple electrodes.

In various embodiments, the tissue motion information can be provided bythe sensor.

In various embodiments, the tissue motion information can be furtherprovided by the multiple electrodes.

In various embodiments, the device can be constructed and arranged toprovide the tissue diagnostic information during a cardiac ablationprocedure.

In various embodiments, the device can be constructed and arranged toprovide tissue diagnostic information while arrhythmia therapy orfunctional therapy is being delivered, wherein such arrhythmia therapyand functional therapy include, but are not limited to, the followingtherapies: ablation, genetic-agent delivery, Cardiac Resynchronization,and pharmacologic.

In various embodiments, the device can be constructed and arranged todeliver ablation energy to tissue.

In various embodiments, the device can be constructed and arranged toprovide precise foci, conduction-gaps, or conduction channels positioninformation.

In various embodiments, the device can be constructed and arranged tolocate foci, boundaries of conduction-gaps, or boundaries of conductionchannels position within 1 mm to 3 mm.

The device of any other claim herein, wherein the device can beconstructed and arranged to provide the location of cardiac tissue withcomplex electrograms.

In various embodiments, the device can be constructed and arranged toprovide at least three locations comprising complex electrograms.

In various embodiments, the device can be constructed and arranged toprovide single beat mapping of cardiac arrhythmias.

In various embodiments, the device can comprise at least one catheterthat is constructed and arranged to be steered and/or guided.

In various embodiments, the catheter can be constructed and arranged tobe steered and/or guided to the sites of complex electrograms by thereal-time tissue analysis and imaging.

In various embodiments, the device can further comprise a deliverysheath.

In various embodiments, the delivery sheath can be constructed andarranged to slidingly receive an ablation catheter.

In various embodiments, the device can further comprise an elongateshaft, comprising a proximal portion with a proximal end and a distalportion with a distal end constructed and arranged to be inserted intothe body of the patient.

In various embodiments, device can further comprise a clamp assemblyconstructed and arranged to be removably attached to the elongate shaftand to transmit vibrational energy.

In various embodiments, the clamp assembly can comprise a vibrationaltransducer configured to emit ultrasound waves.

In various embodiments, the clamp assembly can comprise a clampingmechanism constructed and arranged to be removably attached to theelongate shaft.

In various embodiments, the clamp assembly can be positioned on theproximal portion of the elongate shaft.

In various embodiments, the device can further comprise a handle whereinthe proximal portion is within 10 centimeters from the handle.

In various embodiments, the elongate shaft can further comprise aconduit constructed and arranged to transmit the ultrasound waves fromthe proximal portion to the distal portion.

In various embodiments, the clamp assembly can be positioned on thedistal portion of the elongate shaft.

In various embodiments, the distal portion can be within 10 centimetersfrom the distal end of the elongate shaft.

In various embodiments, the device can further comprise multipleelectrodes wherein the multiple electrodes are positioned on the distalend of the elongate shaft and the clamp assembly is constructed andarranged to vibrate the multiple electrodes.

In various embodiments, the multiple electrodes can comprise themultiple electrodes described above.

In various embodiments, the device can further comprise at least onethermocouple positioned on the elongate shaft wherein the clamp assemblyis constructed and arranged to vibrate the at least one thermocouple.

In various embodiments, the device can further comprise at least onesupport arm attached to the elongate shaft wherein the clamp assembly isconstructed and arranged to vibrate the at least one support arm.

In various embodiments, the device can comprise at least one support armcomprises at least one of a sensor or a transducer.

In various embodiments, the device can further comprise at least oneablation element attached to the elongate shaft wherein the clampassembly is constructed and arranged to vibrate the at least oneablation element.

In various embodiments, the device can further comprise at least onesensor attached to the elongate shaft wherein the clamp assembly isconstructed and arranged to vibrate the at least one sensor where thesensor is selected from the group consisting of: temperature; pressure;electrical signal; electrode; sound; and combinations of these.

In various embodiments, the device can further comprise at least onetransducer attached to the elongate shaft wherein the clamp assembly isconstructed and arranged to vibrate the at least one transducer wherethe transducer is selected from the group consisting of: ablationelement; electrode; sound; and combinations of these.

In various embodiments, the device can further comprise at least oneultrasound crystal positioned on the elongate shaft wherein the clampassembly is constructed and arranged to vibrate the at least onecrystal.

In various embodiments, the clamp assembly can be constructed andarranged to vibrate the elongate shaft.

In various embodiments, the clamp assembly can be positioned such thatthe clamp assembly is located outside the patient's body while thedistal end of the elongate shaft is located within the patient's body.

In various embodiments, at least one of the sensor or the transducer canbe constructed and arranged to clamp to a shaft.

In various embodiments, the device can comprise a shaft and at least oneof the sensor or the transducer is constructed and arranged to clamp tosaid device shaft.

In various embodiments, at least one of the sensor or the transducer canbe constructed and arranged to be slidingly received by a shaft.

In various embodiments, at least one of the sensor or the transducer canbe constructed and arranged to be positioned at a geometric center ofthe multiple electrodes.

In various embodiments, at least one of the sensor or the transducer cancomprise a single component.

In various embodiments, the single component can comprise a singlecrystal.

In various embodiments, at least one of the sensor or the transducer canbe constructed and arranged to be rotated.

In various embodiments, at least one of the sensor or the transducer canbe constructed and arranged to be rotated 360°.

In various embodiments, at least one of the sensor or the transducer canbe constructed and arranged to be translated along an axis.

In various embodiments, at least one of the sensor or the transducer cancomprises an array of components.

In various embodiments, the array can comprise an array of ultrasoundcrystals.

In various embodiments, the array can comprise a circumferential array.

In various embodiments, at least one of the sensor or the transducer canbe positioned in or proximate to at least one of the multipleelectrodes.

In various embodiments, at least one of the sensor or the transducer cancomprise a first component and a second component and wherein the firstcomponent is mounted in or proximate to a first electrode of themultiple electrodes and the second component is mounted in or proximateto a second electrode of the multiple electrodes.

In various embodiments, at least one of the sensor or the transducer cancomprise piezoelectric film.

In various embodiments, the device can further comprise a wireelectrically connected to a first electrode and wherein thepiezoelectric film covers at least a portion of said wire.

In various embodiments, at least one of the sensor or the transducer cancomprise piezoelectric cable.

In various embodiments, the device can comprise a multiple arm assemblyand wherein the at least one of the sensor or the transducer is mountedto the multiple arm assembly.

In various embodiments, a first electrode of the multiple electrodes canbe mounted to the multiple arm assembly.

In various embodiments, at least one of the sensor or the transducer canbe integral to at least one electrode of the multiple electrodes.

In various embodiments, at least one of the sensor or the transducer cancomprise a first surface, and wherein at least one electrode of themultiple electrodes can comprise a second surface, and wherein the firstsurface and the second surface are parallel.

In various embodiments, at least one of the sensor or the transducer canbe constructed and arranged to rotate and transmit or receive signals toor from the cardiac chamber.

In various embodiments, the transducer can comprise an ultrasoundtransducer.

In various embodiments, the transducer can be constructed and arrangedto produce sound waves in at least one of either constant or pulsedexcitation.

In various embodiments, the transducer can comprise multipletransducers.

In various embodiments, the transducer can produce signals with afrequency between 3 Mhz and 18 Mhz.

In various embodiments, the transducer can be constructed and arrangedto clamp on a shaft.

In various embodiments, the device can comprise a shaft and wherein thetransducer is constructed and arranged to clamp on said device shaft.

In various embodiments, the sensor can comprise an ultrasound sensor.

In various embodiments, the sensor can comprise multiple sensors.

In various embodiments, the sensor can be constructed and arranged toclamp on a shaft.

In various embodiments, the device can comprise a shaft and wherein thesensor is constructed and arranged to clamp on said device shaft.

In various embodiments, the device can further comprise: a firstreceiver constructed and arranged to receive mapping information fromthe multiple electrodes, the mapping information received when themultiple electrodes are placed in the one or more cardiac chambers; adipole density module constructed and arranged to generate the threedimensional database of dipole densities d(y), wherein the dipoledensity module determines a dipole density for individual triangleshaped projections onto the cardiac chamber wall, where each triangleprojection at a location y contributes {acute over (ω)}(x,y) times thedipole density d(y) to a potential V(x) at a point x. Here {acute over(ω)}(x,y) is the solid angle for that triangle projection, and where: a)x represents a series of locations within one or more cardiac chambers;and b) V(x) is a measured potential at point x, said measured potentialrecorded by the multiple electrodes.

In various embodiments, the device further comprise: a second receiverconstructed and arranged to receive anatomical information from at leastone imaging instrument configured to produce a geometrical depiction ofthe one or more cardiac chambers.

In various embodiments, said triangle projections can be sized such thatthe dipole density for each triangle projection is substantiallyconstant.

In various embodiments, the dipole density can be determined for atleast 1000 triangle shaped projections.

In various embodiments, the dipole density can be determined by a numberof triangle shaped projections, said number determined by the size of acardiac chamber.

In various embodiments, the multiple electrodes can be included in asingle catheter.

In various embodiments, the multiple electrodes can be included in twoor more catheters.

In various embodiments, the imaging instrument can be selected from agroup consisting of: a computed tomography (CT) instrument; a magneticresonance imaging (MRI) instrument; an ultrasound instrument; a multipleelectrode mapping catheter and mapping system; and combinations thereof.

In various embodiments, the imaging instrument can comprise a standardanatomical geometry which is uploaded to the dipole density module.

In various embodiments, the dipole density module can include amathematical processing element that comprises one or more of: acomputer; an electronic module; a computer program stored in a memoryand executable by a processor; a microcontroller; a microprocessor; andcombinations thereof.

In various embodiments, the dipole density module can be configured toimplement a progressive algorithm configured to improve at least one ofa spatial resolution and a time resolution of the database of dipoledensities d(y).

In various embodiments, the dipole density module can use a linearsystem of equations to determine the database of dipole densities d(y).

In various embodiments, the dipole density module can be configured todetermine a map of dipole densities d(y) at corresponding timeintervals.

In various embodiments, the dipole density module is configured togenerate a synthesis of maps that represents a cascade of activationsequences of each corresponding heart beat from a series of heart beats.

In various embodiments, a number of measured potentials V(x) can be in arange of up to 100,000 potentials V(x).

In various embodiments, the cardiac wall can be divided into regions,wherein each region is represented by a region solid angle with respectto each electrode, and wherein each region solid angle is the sum of thesolid angles of the individual triangles in the region.

In various embodiments, a number of regions used to determine the dipoledensity d(y) can be in a range of up to 100,000 regions on the cardiacwall.

In various embodiments, the measured potentials V(x) can be interpolatedto increase the number of regions.

In various embodiments, V(x) can be interpolated using splines.

In various embodiments, the device can further comprise: a thirdreceiver configured to receive mapping information from one or more skinelectrodes.

In various embodiments, the dipole density module can use said mappinginformation from the one or more skin electrodes to calculate and/orrecalculate the database of dipole densities d(y).

In various embodiments, the dipole density module can calculate and/orrecalculate the dipole densities d(y) using at least one of thefollowing equations:

$\begin{matrix}{W_{k} = {\sum\limits_{l = 1}^{L}{A_{kl}V_{l}}}} & (1)\end{matrix}$

wherein a small sinusoidal voltage Vl is applied to each electrode l=1,. . . L on the electrode array in the heart, and the resulting voltagesWk, k=1, . . . K is measured at the surface electrodes, which yields theKXL transition matrix.

$\begin{matrix}{V_{l} = {\sum\limits_{n = 1}^{N}B_{\ln \mspace{14mu} d_{n}}}} & (2)\end{matrix}$

wherein calculating solid angles produces the linear transformation Bln,between the electrode array potentials Vl and the dipole densities dn,n=1, . . . N of N regions of the heart wall; and

$\begin{matrix}{W_{k} = {\sum\limits_{l = 1}^{L}{\sum\limits_{n = 1}^{N}{A_{kl}B_{\ln \mspace{14mu} d_{n}}}}}} & (3)\end{matrix}$

where equation (2) above is substituted into equation (1) to formequation (3).

In various embodiments, the dipole density module can be configured tosolve equations (2) and (3) using regularization techniques.

In various embodiments, the regularization technique can comprise aTikhonov regularization.

In accordance with another aspect of the invention, provided is a systemfor creating a database of dipole densities d(y) and distancemeasurements at the surface of one or more cardiac chambers of apatient. The system comprise: a device for creating a database of dipoledensities d(y) at the surface of one or more cardiac chambers of apatient, comprising: multiple electrodes located on one or morecatheters; a first receiver configured to receive mapping informationfrom the multiple electrodes, the mapping information received when themultiple electrodes are placed in the one or more cardiac chambers; asecond receiver configured to receive anatomical information from atleast one imaging instrument configured to produce a geometricaldepiction of the one or more cardiac chambers; a dipole density moduleconfigured to generate the database of dipole densities d(y), whereinthe dipole density module determines a dipole density for individualtriangle shaped projections onto the cardiac chamber wall, where eachtriangle projection at a location y contributes {acute over (ω)}(x,y)times the dipole density d(y) to a potential V(x) at a point x, wherein{acute over (ω)}(x,y) is the solid angle for that triangle projection,and wherein: a) x represents a series of locations within one or morecardiac chambers; and b) V(x) is a measured potential at point x, saidmeasured potential recorded by the multiple electrodes.

In various embodiments, the system can further comprise a second imaginginstrument.

In various embodiments, the system can comprise a catheter for mappingand ablation.

In various embodiments, the system can comprise an ablation deviceconfigured to deliver one or more of: radio frequency (RF) energy;ultrasound energy, and cryogenic energy.

In various embodiments, the system can comprise a device configured todeliver one or more of the following therapies: genetic-agent delivery,cardiac resynchronization, and pharmacologic.

In accordance with another aspect of the invention, provided is a methodof creating a database of dipole densities d(y) and distancemeasurements at the surface of one or more cardiac chambers of apatient. The method comprises: placing a distal end of an electrodecatheter into one of the one or more cardiac chambers of a patient; andcalculating dipole densities d(y) by: a first receiver receiving mappinginformation from multiple electrodes located on one or more catheters,the mapping information received when the multiple electrodes are placedin the one or more cardiac chambers; a second receiver receivinganatomical information from at least one imaging instrument configuredto produce a geometrical depiction of the one or more cardiac chambers;and a dipole density module generating the database of dipole densitiesd(y), wherein the dipole density module determines a dipole density forindividual triangle shaped projections onto the cardiac chamber wall,where each triangle projection at a location y contributes {acute over(ω)}(x,y) times the dipole density d(y) to a potential V(x) at a pointx, wherein {acute over (ω)}(x,y) is the solid angle for that triangleprojection, and where: a) x represents a series of locations within oneor more cardiac chambers; and b) V(x) is a measured potential at pointx, said measured potential recorded by the multiple electrodes; andcalculating distance or movement information by analyzing signalsreceived from a sound sensor.

In various embodiments, the method can comprise calculating distanceinformation comprises calculating tissue thickness information.

In various embodiments, the method can comprise using the dipoledensities d(y) to locate an origin of abnormal electrical activity of aheart.

In various embodiments, wherein calculating the dipole densities caninclude a processor executing a computer program stored in a memory, thecomputer program embodying an algorithm for generating a table of dipoledensities in the memory.

In accordance with another aspect of the invention, provided is a methodfor diagnosing tissue, said method comprising: placing a distal end of acatheter into one or more cardiac chambers of a patient; wherein thecatheter comprises at least one electrode and at least one ultrasoundelement; determining a tissue movement via the at least one ultrasoundelement; determining an electrical charge via the at least oneelectrode; and determining tissue diagnostics based upon the tissuemovement and the electrical charge.

In accordance with another aspect of the invention, provided is amedical method comprising: inserting a device of any of claim 1 through122 into a delivery system; advancing the device through the deliverysystem and into a heart chamber; and steering the device and/or thedelivery system such that the distal end of the device is positioned inapproximately the geometric center of the heart chamber.

In accordance with another aspect of the invention, provided is a methodof diagnosing tissue of a patient, comprising: combining electricalinformation and anatomical information; wherein the electricalinformation comprises information received from multiple electrodesconstructed and arranged to record electrical signals produced bytissue; and wherein the anatomical information comprises informationreceived by a sensor constructed and arranged to record sound signals.

In various embodiments, the electrical information indicative ofadequate electrical activity and anatomical information indicative ofadequate tissue motion can correlate to presence of healthy tissue.

In various embodiments, the electrical information indicative ofadequate electrical activity and anatomical information indicative ofinadequate tissue motion can correlate to presence of at least one ofischemic tissue or hibernating tissue.

In various embodiments, the electrical information can comprise signalslarger than a threshold voltage.

In various embodiments, the electrical information indicative ofinadequate electrical activity and anatomical information indicative ofinadequate tissue motion can correlate to presence of scar tissue.

In various embodiments, the diagnosis can comprise an assessment oftissue ischemia.

In various embodiments, the diagnosis comprises an assessment ofelectrical integrity of cardiac cells.

In various embodiments, the diagnosis can further comprise an assessmentof the functional status of the cardiac cells.

In various embodiments, the electrical information indicative ofinadequate electrical activity and anatomical information indicative ofinadequate tissue motion can correlate to presence of a completeablation such as an ablation performed in a cardiac ablation performedto treat a cardiac arrhythmia.

In various embodiments, the complete ablation can comprise a transmuralablation.

In various embodiments, the electrical information can comprise dipoledensity information.

In various embodiments, the electrical information can comprise at leastone of the following: depolarization, repolarization, speed of wavefrontpropagation, magnitude of voltage (max, min, gradient), timing ofactivation, and duration of activation.

In various embodiments, the method can further comprise ablating cardiactissue by applying ablation energy for a time period.

In various embodiments, the anatomical information can comprise tissuethickness information and at least one of the ablation energy or thetime period is adjusted based on the tissue thickness information.

In accordance with aspects of the present invention, provided is amethod for performing a medical procedure on a patient, the methodcomprising: inserting a first catheter into the patient, wherein thefirst catheter comprises a first set of elements and at least onesensor; inserting a second catheter into the patient, wherein the secondcatheter comprises an elongate shaft and wherein the second cathetercomprises a second set of elements; and attaching a clamp assembly tothe second catheter, wherein the clamp assembly is constructed andarranged to be removably attached to the second catheter and to transmitvibrational energy.

In various embodiments, the first set of elements can comprise a sensor.

In various embodiments, the sensor can be selected from a groupconsisting of: temperature; pressure; electrical signal; electrode;sound; and combinations of these.

In various embodiments, the first set of elements can comprise atransducer.

In various embodiments, the transducer can be selected from the groupconsisting of: ablation element; electrode; sound; and combinations ofthese.

In various embodiments, the at least one sensor can comprise anultrasound sensor.

In various embodiments, the at least one sensor can comprise atransducer.

In various embodiments, the transducer can comprise an ultrasoundtransducer.

In various embodiments, the second set of elements can comprise asensor.

In various embodiments, the sensor can be selected from the groupconsisting of: temperature; pressure; electrical signal; electrode;sound; and combinations of these.

In various embodiments, the second set of elements can comprises atransducer.

In various embodiments, the transducer can be selected from a groupconsisting of: ablation element; electrode; sound; and combinations ofthese.

In various embodiments, the second catheter elongate shaft can comprisea proximal portion with a proximal end and a distal portion with adistal end.

In various embodiments, the clamp assembly can comprise a vibrationaltransducer configured to emit ultrasound waves.

In various embodiments, the clamp assembly can comprise a clampingmechanism constructed and arranged to be removably attached to thesecond catheter elongate shaft.

In various embodiments, the clamp assembly can be positioned on theproximal portion of the second catheter elongate shaft.

In various embodiments, the second catheter can comprise a handle.

In various embodiments, the clamp assembly can be positioned within 10centimeters from the handle.

In various embodiments, the second catheter elongate shaft can furthercomprise a conduit constructed and arranged to transmit the ultrasoundwaves from the proximal portion to the distal portion of the secondcatheter elongate shaft.

In various embodiments, the clamp assembly can be positioned on thedistal portion of the second catheter elongate shaft.

In various embodiments, the second catheter distal portion can be within10 centimeters from the distal end of the second catheter elongateshaft.

In various embodiments, the second catheter elongate shaft can furthercomprise multiple electrodes wherein the multiple electrodes arepositioned on the distal end of the second catheter elongate shaft andthe clamp assembly is constructed and arranged to vibrate the multipleelectrodes.

In various embodiments, the multiple electrodes can comprise themultiple electrodes described above.

In various embodiments, the second catheter elongate shaft can furthercomprise at least one thermocouple positioned on the second catheterelongate shaft wherein the clamp assembly is constructed and arranged tovibrate the at least one thermocouple.

In various embodiments, the second catheter elongate shaft can furthercomprise at least one support arm attached to the second catheterelongate shaft wherein the clamp assembly is constructed and arranged tovibrate the at least one support arm.

In various embodiments, the at least one support arm can comprise atleast one of a sensor or a transducer.

In various embodiments, the second catheter elongate shaft can furthercomprise at least one ablation element attached to the second catheterelongate shaft wherein the clamp assembly can be constructed andarranged to vibrate the at least one ablation element.

In various embodiments, the second catheter elongate shaft can furthercomprise at least one sensor attached to the second catheter elongateshaft wherein the clamp assembly can be constructed and arranged tovibrate the at least one sensor where the sensor is selected from thegroup consisting of: temperature; pressure; electrical signal;electrode; sound; and combinations of these.

In various embodiments, the second catheter elongate shaft can furthercomprise at least one transducer attached to the second catheterelongate shaft wherein the clamp assembly can be constructed andarranged to vibrate the at least one transducer where the transducer isselected from the group consisting of ablation element; electrode;sound; and combinations of these.

In various embodiments, the second catheter elongate shaft can furthercomprise at least one ultrasound crystal positioned on the secondcatheter elongate shaft wherein the clamp assembly can be constructedand arranged to vibrate the at least one crystal.

In various embodiments, the clamp assembly can be constructed andarranged to vibrate the second catheter elongate shaft.

In various embodiments, the clamp assembly can be positioned such thatthe clamp assembly can be located outside the patient's body while thedistal end of the second catheter elongate shaft is located within thepatient's body.

Provided is device, system, and/or method for real time, non-contactimaging and distance measurements using ultrasound for dipole densitymapping, as well as methods for diagnosing tissue health, as depicted inthe drawings included herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate various embodiments in accordancewith the present invention, and together with the description, serve toexplain the principles of the inventions.

FIG. 1 illustrates a schematic view of an embodiment of a device fordetermining a database table of dipole densities d(y) of at least oneheart chamber, consistent with aspects of the present invention.

FIG. 2 illustrates a flow chart of an embodiment of a preferred methodfor determining a database table of dipole densities of at least oneheart chamber, consistent with aspects of the present invention.

FIG. 3 illustrates a schematic view of an embodiment of a system fordetermining a database table of dipole densities of at least one heartchamber with help of the solid angle {acute over (ω)}(x,y) consistentwith aspects of the present invention.

FIG. 4 illustrates a side view of an end portion of a cathetercomprising ultrasound elements attached to multiple support arms,consistent with aspects of the present invention.

FIG. 5 illustrates a side view of a system including a mapping cathetercomprising multiple sensors, an ablation catheter comprising multipleablation elements and a clamping assembly attached to the ablationcatheter, consistent with aspects of the present invention.

FIG. 6 illustrates a flow chart of an embodiment of a preferred methodfor diagnosing the tissue of a patient, consistent with aspects of thepresent invention.

DETAILED DESCRIPTION

A device for calculating surface charge densities has been described indetail in PCT International Application Number PCT/CH2007/000380(hereinafter the '380 patent application), filed Aug. 3, 2007, andentitled METHOD AND DEVICE FOR DETERMINING AND PRESENTING SURFACE CHARGEAND DIPOLE DENSITIES ON CARDIAC WALLS.

As discussed in the '380 patent application, research indicated that theuse of the surface charge densities (i.e. their distribution) or dipoledensities (i.e. their distribution) to generate distribution map(s)would lead to more detailed and precise information on electric ionicactivity of local cardiac cells than potentials. Surface charge densityor dipole densities represent precise and sharp information of theelectric activity with a good spatial resolution, whereas potentialsresulting from integration of charge densities provide only a diffusepicture of electric activity. The electric nature of cardiac cellmembranes comprising ionic charges of proteins and soluble ions can beprecisely described by surface charge and dipole densities. The surfacecharge densities or dipole densities cannot be directly measured in theheart, but instead must be mathematically and accurately calculatedstarting from measured potentials. In other words, the information ofvoltage maps obtained by current mapping systems can be greatly refinedwhen calculating surface charge densities or dipole densities fromthese.

The surface charge density means surface charge (Coulombs) per unit area(cm²). A dipole, as such, is a neutral element, wherein a part comprisesa positive charge and the other part comprises the same but negativecharge. A dipole might represent the electric nature of cellularmembranes better, because in biological environment ion charges are notmacroscopically separated.

In order to generate a map of surface charge densities (surface chargedensity distribution) according to the '380 patent application, thegeometry of the given heart chamber must be known. The 3D geometry ofthe cardiac chamber is typically assessed by currently available andcommon mapping systems (so-called locator systems) or, alternatively, byintegrating anatomical data from CT/MRI scans. For the measurement ofpotentials the non-contact mapping method a probe electrode was used.The probe electrode may be a multi-electrode array with elliptic orspherical shape. The spherical shape has certain advantages for thesubsequent data analysis. But also other types or even severalindependent electrodes could be used to measure V_(e). For example, whenconsidering the ventricular cavity within the endocardium and taking aprobe electrode with a surface S_(P), which is located in the blood, itis possible to measure the potential V(x,y,z) at point x,y,z on thesurface S_(P). In order to calculate the potential at the endocardialsurface S_(e) the Laplace equation:

$\begin{matrix}{{\Delta \; V} = {{\left( {\frac{\partial^{2}}{\partial x^{2}} + \frac{\partial^{2}}{\partial y^{2}} + \frac{\partial^{2}}{\partial z^{2}}} \right)V} = 0}} & (1)\end{matrix}$

needs to be solved, wherein V is the potential and x,y,z denote thethree dimensional coordinates. The boundary conditions for this equationare V(x,y,z)=V_(P)(x,y,z) on S_(P), wherein V_(P) is the potential onsurface of the probe.

The solution is an integral that allows for calculating the potentialV(x′y′z′) at any point x′y′z′ in the whole volume of the heart chamberthat is filled with blood. For calculating said integral numerically adiscretisation of the cardiac surface is necessary and the so calledboundary element method (BEM) has to be used.

The boundary element method is a numerical computational method forsolving linear integral equations (i.e. in surface integral form). Themethod was applied in many areas of engineering and science includingfluid mechanics, acoustics, electromagnetics, and fracture mechanics.

The boundary element method is often more efficient than other methods,including the finite element method. Boundary element formulationstypically give rise to fully populated matrices after discretisation.This means, that the storage requirements and computational time willtend to grow according to the square of the problem size. By contrast,finite element matrices are typically banded (elements are only locallyconnected) and the storage requirements for the system matricestypically grow quite linearly with the problem size.

With the above in mind, all potentials V_(P) (x1′y1′z1′) on the surfaceof the probe can be measured. To calculate the potential V_(e) on thewall of the heart chamber, the known geometry of the surface of theheart chamber must be divided in discrete parts to use the boundaryelement method. The endocardial potentials V_(e) are then given by alinear matrix transformation T from the probe potentials V_(P): V_(e)=TV_(P).

After measuring and calculating one or more electric potential(s) V_(e)of cardiac cells in one or more position(s) P(x,y,z) of the at least onegiven heart chamber at a given time t. The surface charge density andthe dipole density are related to potential according to the followingtwo Poisson equations:

$\begin{matrix}{{\Delta \; V_{e}} = {{\rho (P)}{\delta_{S_{e}}(P)}}} & (2) \\{{\Delta \; V_{e}} = {\frac{\delta}{\partial n}\left( {v\; {\delta_{S_{e}}(P)}} \right)}} & (3)\end{matrix}$

wherein ρ(P) is the surface charge density in position P=x,y,z, δ_(S)_(e) (P) is the delta-distribution concentrated on the surface of theheart chamber S_(e) and υ is the dipole density.

There is a well known relationship between the potential V_(e) on thesurface of the wall of the heart chamber and the surface charge (4) ordipole densities (5).

$\begin{matrix}{{V_{e}(P)} = {{- \frac{1}{4\pi}}{\int_{S_{e}}{\frac{\rho \left( P^{\prime} \right)}{{P^{\prime} - P}}{{\sigma \left( P^{\prime} \right)}}}}}} & (4) \\{{V_{e}(P)} = {\frac{1}{4\pi}{\int_{S_{e}}{{v\left( P^{\prime} \right)}\frac{\partial}{\partial n_{P^{\prime}}}\frac{1}{{P - P^{\prime}}}{{\sigma \left( P^{\prime} \right)}}}}}} & (5)\end{matrix}$

(For a review see Jackson J D. Classical Electrodynamics, 2^(nd)edition, Wiley, New York 1975.)

The boundary element method again provides a code for transforming thepotential V_(e) in formulas 4 and 5 into the desired surface chargedensities and dipole densities, which can be recorded in the database.

In another embodiment of the method, the electric potential(s) V_(e) is(are) determined by contact mapping. In this case the steps forcalculating the electric potential V_(e) are not necessary, because thedirect contact of the electrode to the wall of the heart chamber alreadyprovides the electric potential V_(e).

In a preferred embodiment, the probe electrode comprises a shape thatallows for calculating precisely the electric potential V_(e) and, thus,simplifies the calculations for transforming V_(e) into the desiredcharge or dipole densities. This preferred geometry of the electrode isessentially ellipsoidal or spherical.

In order to employ the method for determining a database table ofsurface charge densities of at least one given heart chamber in thecontext of the '380 patent application, it was preferred to use a systemcomprising at least:

-   -   a) one unit for measuring and recording electric potentials V at        a given position P(x,y,z) on the surface of a given heart        chamber (Contact mapping) or a probe electrode positioned within        the heart, but without direct wall contact (noncontact mapping)    -   b) one A/D-converter for converting the measured electric        potentials into digital data,    -   c) one memory to save the measured and/or transformed data, and    -   d) one processor unit for transforming the digital data into        digital surface charge density or dipole density data.

It is noted that numerous devices for localising and determiningelectric potentials of cardiac cells in a given heart chamber byinvasive and non-invasive methods are well known in the art and havebeen employed by medical practitioners over many years. Hence, themethod, system, and devices of the '380 patent application did notrequire any particular new electrodes for implementing the best mode forpracticing the invention. Instead, the '380 patent application provideda new and advantageous processing of the available data that will allowfor an increase in precision, accuracy and spatial resolution of cardiacactivation mapping when compared to prior art systems based on electricsurface potentials in the heart only. The systems and methods of the'380 patent application would also allow for providing superiordiagnostic means for diagnosing cardiac arrhythmias and electric statusof heart cells including metabolic and functional information.

The present invention provides an improved device, system and method forcalculating and visualizing the distribution and activity of dipolecharge densities on a cardiac wall. The dipole densities are directlydetermined geometrically, avoiding the errors encountered using previousextrapolation algorithms.

In one embodiment, the device of the present invention comprisesmultiple electrodes located on one or more catheters, a transducer, anda sensor. The device may be used to create a three dimensional databaseof dipole densities d(y) and distance measurements at the surface of oneor more cardiac chambers of a patient. The distance measurements mayinclude but are not limited to: the distance between at least one of themultiple electrodes and the heart wall, the distance between at leastone of the multiple electrodes and the transducer and/or sensor, and thedistance between the heart wall and the transducer and/or sensor. Thedistance measurements may be calculated by analyzing the sensor recordedangle and/or the sensor frequency changes. The device may also beconfigured to produce continuous, real time images of the tissue of apatient. Examples of images may include, but are not limited to: onemore cardiac chambers, a cardiac wall, the tissue proximate at least oneof the multiple electrodes, at least one of the multiple electrodes, andcombinations of these. The device may provide one or more of: tissueimage information such as tissue position, tissue thickness (e.g.cardiac wall thickness) and tissue motion (e.g. cardiac wall motion)information; distance information such as distance between two tissuelocations, distance between a tissue location and a device componentlocation, and distance between two device component locations; tissueelectrical activity information; status of ablation of a portion oftissue; and combinations of these.

The present invention incorporates a transducer and a sensor, eachpreferably ultrasonic and contained in a single component. Thetransducer and sensor are configured to determine a non-contactmeasurement of the distance or presence of one or more targets such astissue of a patient or a component of one or more catheters or otherdevices. Information is produced by transmitting an ultrasound wavefollowed by measuring the time required for the sound echo to return toand be sensed by the sensor, thus determining the distance between allreflected surfaces and the sensor/transmitter. This additionalinformation enables a more precise dipole density d(y) measurement.Measurements may be taken to determine the thickness of an object, suchas the thickness of cardiac tissue, which may be used to determine anablation parameter such as power or time of energy delivery.

Utilizing the present invention, a method for diagnosing tissue is alsodisclosed. Analyzing the information gathered from a catheter device,specifically the tissue movement and the tissue's electrical charge, aclinician is able to determine the health of the tissue. For example, ifadequate tissue movement has been detected, and the tissue produces anelectrical signal indicative of a healthy state, then the tissue isdetermined to be healthy. With the tissue diagnosis, a clinician maydetermine what type of treatment, e.g. ablation, is favorable to thepatient.

In accordance with the present invention, provided is a device thatmeasures and calculates a database of dipole densities d(y) on thecardiac wall. The actual measured potentials in the heart result fromelectrical activity of cells, which can be regarded as dipoles. Thedipoles consist of ion charges on both sides of biological membranes.The use of dipole densities offers a precise representation of theelectrical activity. Systems and methods in accordance with the presentinvention efficiently and effectively calculate the dipole densitiesutilizing one or more mathematical theorems. This calculation issignificantly more precise than calculations of virtual potentialsproduced by current systems, which lose spatial precision because of therequired numerical methods and the use of potentials instead of dipoledensities. Systems and methods in accordance with the present inventionare efficient in calculating dipole densities geometrically, such asthrough the use of computer systems, or similar microcontroller and/ormathematical processing equipment.

Definitions. To facilitate an understanding of the invention, a numberof terms are defined below.

As used herein, the terms “subject” and “patient” refer to any animal,such as a mammal like livestock, pets, and preferably a human. Specificexamples of “subjects” and “patients” include, but are not limited to,individuals requiring medical assistance, and in particular, patientswith an arrhythmia such as atrial fibrillation (AF).

As used herein, in the illustrative embodiments, the term “solid angle”is the two-dimensional angle subtended in the three dimensional spacebetween a triangle on the heart wall and the position x of observation.When viewed from location x, straight lines are drawn from point x tothe vertices of the triangle, and a sphere is constructed of radius r=1with center of x. The straight lines then define a triangular section onthe surface of the unit sphere. The solid angle is equal to the surfacearea of that triangle. As used herein, in the illustrative embodiments,the term “dipole density” refers to a three dimensional table of densitymagnitudes and d(y) generally refers to three dimensional system orspace.

The methods and devices of the present invention have advantages overprevious prior art devices. FIGS. 1-6 illustrate various preferredembodiments of devices, systems and methods in accordance with aspectsof the present invention. However, the present invention is not limitedto these particular configurations.

Referring now to FIG. 1, a schematic view of an embodiment of a devicefor determining a database table of dipole densities of at least oneheart chamber of a patient is illustrated. Device 100 includes a firstreceiver 110 configured to receive electrical potentials from a separatedevice, such as a device including a multi-electrode mapping catheterplaced in the circulating blood within a chamber of the patient's heart.Device 100 further includes a second receiver 120 configured to receivecardiac geometry information (e.g. the geometric contour of the cardiacchamber wall), such as from an instrument including, but not limited to:Computed Tomography; MRI; Ultrasound; a multi-electrode mappingcatheter; and combinations of these. Alternatively, a standard geometrycan be loaded representing a model of the cardiac chamber.

Device 100 further comprises a third receiver 140 configured receiveultrasound information from ultrasound unit 240. Ultrasound unit 240comprises a transducer and sensor. In a preferred embodiment, thetransducer comprises an ultrasound transducer configured to produce highfrequency vibrations, i.e., ultrasound waves, in a pulsed or constantmanner. Typically, the ultrasound transducer produces sound waves havinga wavelength of 5-15 MHz. In some embodiments, the transducer and thesensor are a single component such as a piezo crystal configured to bothtransmit and sense ultrasound signals.

In this embodiment, the sensor is preferably an ultrasound sensorconfigured to record or otherwise detect the emitted ultrasound wavesfrom the ultrasound transducer. The sensor may be further configured todetermine real-time continuous measurements of the position of at leastone of the multiple electrodes and/or the sensor within the cardiacchamber. Knowing the speed of sound in the particular environment, aswell as the timing of the delivery of sound waves by the transducer, thedistance between the sensor, transducer and one or more reflectedsurfaces can be calculated.

In a typical embodiment, a piezo crystal transmits ultrasound waves andreceives the reflections of those waves. As is well known to those ofskill in the art, the timing between transmitting and receiving can beused to determine locations of the reflective surfaces such as tissuesurfaces and device component surfaces. In one embodiment, preciselocations and measurements of target cardiac tissue is determined,resulting in a more precise and effective therapy. The ultrasoundcrystal will transmit a signal that is reflected off of tissue surfaces,which can be used to determine the distance from the mapping electrodeto the tissue. This distance will be fed into the software algorithm toaid in the calculation of electrical activity via dipole density ordirect electrical signal analysis.

By having the precise distance, the overall calculations will be veryprecise (frequency; it is approximately 3 megahertz and may be up to the18 megahertz). The emitted waves may be at constant frequency orproduced by a chip of changing frequency (to allow pulse compression onreception). The precision in dipole density calculations along with thedistance measurement will allow for the precise detailing of the cardiaccells in the electrical activity and will allow for the preciseidentification of cell activity to identify which cells are the earliestsites of activation. In one embodiment, the sensor may be configured toautomatically detect the distance from the sensor to the cardiac wallvia a first reflection and detect the wall thickness via a secondreflection. Other distances measurements include, but are not limitedto: the distance between at least one of the multiple electrodes and theheart wall, the distance between at least one of the multiple electrodesand the transducer and/or sensor, and the distance between the heartwall and the transducer and/or sensor. In another embodiment, theultrasonic element integrates multiple reflections to construct acomplete image including wall distance and thickness. In yet anotherembodiment, the ultrasonic element provides information relative to thepositioning of the cardiac tissue and one or more electrodes, such as tolocalize an ablation and/or a mapping catheter including those one ormore electrodes.

In one embodiment, the sensor and/or transducer includes at least onecrystal, typically comprised of a piezoelectric material, which ispositioned proximate to the center of each electrode within an electrodearray. In another embodiment, the crystal is positioned between two ormore electrodes, such as to create a device with a ratio of mappingelectrodes to crystals of 1:1, 2:1, 5:2, 3:1, 4:1 or another ratio. Theat least one crystal may be constructed and arranged to receive thesignals transmitted by an ultrasound transducer, and/or the reflectionsof those signals. The at least one crystal may be in a fixed position ormay be rotated via a rotating mechanism such as by a rotating shaftoperably attached to the at least one ultrasound crystal. The rotationmay be a full rotation, e.g. 360°, such that the full circumference ofthe cardiac chamber is measured. Alternatively, the rotation of the atleast one crystal may be partial. Alternatively or additionally, one ormore ultrasound crystals may be moved axially, such as in areciprocating motion to produce an image of an increased length and/orto produce a 3-D reconstructed image. In another embodiment, the sensorand/or transducer comprise a plurality of crystals arranged in an array,for example, a circumferential array.

In another embodiment, the ultrasound sensor and/or transducer maycomprise a probe operably attached to the catheter and configured tovibrate one or more catheter components. In an alternate embodiment, theultrasound sensor and/or transducer comprise a piezoelectric filmcovering each electrode within the array. In yet another embodiment, theultrasound sensor and/or transducer comprise a piezoelectric cableoperably connected to each electrode.

The ultrasound sensor and/or transducer may be housed within amechanical clamping assembly which may be attached to the shaft of acatheter, such as a mapping catheter or an ablation catheter.Additionally, a particular clamping assembly with a particularultrasound frequency may be used with a particular catheter, while asecond clamping assembly with a second ultrasound frequency may be usedwith a second catheter. In another embodiment, the ultrasound sensorand/or transducer may be directly inserted into the mapping catheter.

In yet another embodiment, the device may comprise a multiple armassembly such that the sensor and/or transducer are mounted to themultiple arm assembly. Additionally, at least one electrode may bemounted to the multiple arm assembly. In an alternate embodiment, thesensor and/or transducer may be constructed as part of the electrode.For example, the device may comprise a sensor/electrode combination. Inanother embodiment, the sensor and/or transducer may be constructed as aforward facing sensor and arranged to project a signal directly in linewith an electrode to the tissue. In yet another embodiment, the sensorand/or transducer may be configured to be rotated such that the sensorand/or transducer is facing each electrode individually, and a signalmay be emitted past each electrode.

In some embodiments, the device is constructed and arranged to besteered such that the distal end of the device is positioned inapproximately the geometric center of the heart chamber of a patient. Inthis embodiment, the catheter may be loaded into a delivery system,e.g., a delivery sheath and may be advanced from the delivery sheathsuch that the dipole density mapping system comprising the ultrasoundsensor is located in the blood and the heart chamber. Also in thisembodiment, the delivery sheath may comprise a central lumen configuredto slidingly receive an ablation catheter. This configuration of thedevice may allow a user to perform a diagnostic procedure with onedevice. Additionally, only one trans-septal crossing may be necessary.In yet another embodiment, the device may be steerable. For example, auser may determine the ablation site via real-time tissue analysis andimaging, and subsequently the device may be steered to the desiredlocation. Steering of the device may be achieved via cables which may behoused in a lumen of a delivery sheath similar to the delivery sheathdescribed above.

Device 100 further includes a dipole density module 130 which comprisesmathematical processing element, such as a computer or other electronicmodule including software and/or hardware for performing mathematical orother calculations. Dipole density module 130 receives mappinginformation from first receiver 110 and cardiac geometry informationfrom second receiver 120. Dipole density module 130 preferably uses oneor more algorithms to process the received mapping and geometryinformation to produce a database table of dipole densities, e.g., athree dimensional database table of dipole densities.

The geometrical model of the cardiac chamber is processed by dipoledensity module 130 into multiple small triangles (triangularization).When the triangles are sufficiently small, the dipole density at eachtriangle can be regarded as constant. In a preferred embodiment, astandard cardiac chamber of 4-6 cm diameter is divided up into over 1000triangles. In another preferred embodiment, the number of trianglesdetermined by dipole density module 130 is based on the size of theheart chamber. With the electrodes positioned in a cardiac chamber by aclinician, such as an electrophysiologist, the potentials at eachelectrode are recorded. Each triangle is seen by the correspondingelectrode under a certain solid angle. The dipole density module 130computes the solid angle {acute over (ω)}(x,y) subtended by eachtriangle at position y on each electrode at position x on themulti-electrode catheter. If the dipole density at the triangle is d(y),the triangle contributes {acute over (ω)}(x,y) times d(y) to thepotential V(x) at the position x on the multi-electrode catheter. Thetotal measured potential V(x) is the sum resulting from all thetriangles. A detailed description is provided in reference to FIG. 3herebelow.

In a preferred embodiment, dipole density module 130 implements aprogressive algorithm that can be modified and/or refined in order toimprove spatial and/or time resolution of the database of dipoledensities that are produced. The dipole densities d(y) are obtained bysolving a linear system of equations. This calculation requires somecare to avoid numerical instabilities. Thereby a map of dipole densitiescan be created at each corresponding time interval. The synthesis of themaps generates a cascade of the activation sequence of eachcorresponding heart beat that can be used to define the origin of theelectrical activity, arrhythmias or diagnose cardiac disease.

The measuring electrodes used in the present invention are placed in theblood flow in a heart chamber, a relatively homogeneous condition, suchthat the mathematical analysis of the present invention is wellapplicable. In a preferred embodiment, skin electrodes are alsoimplemented such that dipole density module 130 can use the informationreceived from the skin electrodes to calculate and/or recalculate thedipole densities for the cardiac wall. The spatial resolution which canbe obtained by invasive (i.e., placed in the heart chamber)multi-electrode potential measurements is limited by the number ofelectrodes that can be placed in any cardiac chamber, such as the LeftAtrium (LA). Skin placed electrodes, such as electrodes placed on thethorax, are not as space limited. However, due mainly to theinhomogeneous structure of the body, it is difficult to localize theactual sources of the skin electrode measured potentials. A highlycomplicated boundary value problem must be solved with boundaryconditions that are poorly known, and previous attempts at determiningthe “action potential” from body surface ECG (alone) have not been verysuccessful.

The badly defined boundary value problem can be avoided by an additionalmeasurement (in addition to the skin electrode measurements) of themulti-electrode array of the present invention. A small sinusoidalvoltage V, is applied to each electrode l=1, . . . L on the electrodearray in the heart, and the resulting voltages W_(k), k=1, . . . K ismeasured at the surface electrodes. This yields the KXL transitionmatrix A_(kl)

$\begin{matrix}{W_{k} = {\sum\limits_{l = 1}^{L}{A_{kl}V_{l}}}} & (6)\end{matrix}$

Calculating solid angles produces the linear transformation B_(ln)between the electrode array potentials V_(i) and the dipole densitiesd_(n), n=1, . . . N of N regions of the heart wall:

$\begin{matrix}{V_{l} = {\sum\limits_{n = 1}^{N}B_{\ln \mspace{14mu} d_{n}}}} & (7)\end{matrix}$

N is chosen to be N=K+L where K is the number of surface electrodes andL is the number of internally placed array electrodes. Substitutingequation (7) into (6) we have:

$\begin{matrix}{W_{k} = {\sum\limits_{l = 1}^{L}{\sum\limits_{n = 1}^{N}{A_{kl}B_{\ln \mspace{14mu} d_{n}}}}}} & (8)\end{matrix}$

Therefore, by simultaneous measuring of the potentials of the cardiacactivity with all K+L electrodes, N=K+L dipole densities of N regions onthe heart wall can be calculated. This method yields a higher spatialresolution than the L array electrodes alone. In the solution of thelinear system of equations (7)+(8), regularization techniques must beused (e.g. Tikhonov regularization and its modifications) in order toavoid numerical instabilities.

Referring now to FIG. 2, an embodiment of a preferred method fordetermining a database table of dipole densities of at least one heartchamber of a patient is illustrated. In Step 10, a multi-electrode arrayis placed within the corresponding heart chamber. In Step 20, thegeometry of the corresponding heart chamber may be obtained in relationto the multi-electrode array position via an ultrasound transducer andsensor, typically a single ultrasound crystal configured to both emitand record ultrasound signals. In addition to chamber geometry,magnitude and other properties of wall motion of cardiac wall tissue canbe determined. For example, an ultrasound transducer positioned on adistal portion of the catheter is configured to transmit ultrasoundwaves to the wall of the cardiac chamber as well as to components of oneor more devices within the cardiac chamber. In an alternativeembodiment, an ultrasound transducer is attached to a proximal portionof a catheter shaft and configured to vibrate the shaft or one or morecomponents mounted to the shaft, thus sending ultrasound waves to thewall of the cardiac chamber. One or more ultrasound sensors detectreflections of the transmitted ultrasound. In addition, the thickness ofa patient's tissue as well as the motion of the tissue may bedetermined, such as to enable a clinician to determine what treatment,(e.g., what ablation parameters) is appropriate for a patient. Adetailed description of one embodiment of the ultrasound transducer andsensor that can be utilized in this step is described in FIG. 1hereabove. Alternatively or additionally, the geometry of thecorresponding heart chamber is obtained in relation to themulti-electrode array position, such as by moving around a secondmapping electrode or by importing a geometry model from an imaging study(e.g., using computed tomography, MRI or ultrasound before or after themulti-electrode array of electrodes has been placed in the heartchamber). The surface of the geometry of the corresponding heart chamberis divided into small triangles, typically at least 1000 smalltriangles.

In Step 30, the dipole density d(y) can be calculated from the measuredpotential values and the calculated solid angles. The measurements canbe repeated successively during the cardiac cycle giving a hightime-resolution during each millisecond. The information of the timelydependent dipole densities can be depicted as an activation map of thecorresponding heart chamber for the given heart beat. The informationcan be used to diagnose and/or treat a patient with a cardiacarrhythmia, such as atrial fibrillation.

In a preferred embodiment, the information is used to determine cardiacwall treatment locations for lesion creation, such as a lesion createdin the Left or Right atrium, by an RF, ultrasound or cryogenic ablationcatheter. In another preferred embodiment, the multiple electrodemapping array is placed in a ventricle and the dipole densities aredetermined for the ventricular wall, such as to detect ischemia orquantify myocardial function.

In one embodiment, the device includes one or more catheters constructedand arranged to be steered such that the distal end of the catheter canbe positioned in approximately the geometric center of the heart chamberof a patient. In this method, a mapping catheter may be loaded into adelivery system (e.g. a delivery sheath) and may be advanced from thedelivery system such that the dipole density mapping system comprisingan ultrasound sensor and transducer is located in the circulating bloodof the heart chamber.

Referring now to FIG. 3, an embodiment of a system for determining adatabase table of dipole densities of at least one heart chamber of apatient is illustrated. System 500 includes device 100, which isconfigured to create a database table of three dimensional dipoledensities d(y) based on voltage potential measurements within the heartchamber and image information relating to the heart chamber, as has beendescribed hereabove. System 500 further includes imaging unit 220, whichis configured to provide a two or three-dimensional image of the heartchamber to device 100. Imaging unit 220 may perform at least one ofComputed Tomography, MRI and/or ultrasound imaging. Imaging unit 220 mayproduce any form of real or virtual models of the cardiac chambers, suchthat a triangularization analysis is possible.

System 500 further includes mapping catheter 310, which includes shaft311, shown inserted into a chamber of a patient's heart, such as theLeft Atrium (LA). At the distal end of shaft 311 is an electrode array315 including multiple electrodes 316. Electrode array 315 is shown in abasket construction, comprising support arms 314, but numerous otherconstructions can be used including multiple independent anus, spiralarrays, electrode covered balloons, and other constructions configuredto place multiple electrodes into a three-dimensional space. In apreferred embodiment, any catheter with a three-dimensional array ofelectrodes can be used to supply the mapping information to device 100.

In this embodiment, electrodes 316 are connected to wires, not shown,but traveling proximally to cable 317, which is electrically connectedto a mapping unit 210, such as an electrocardiogram (ECG) unit. Mappingunit 210 includes a monitor for displaying information, such as thepotentials recorded by electrodes 316, as well as the dipole densityinformation produced by device 100. In an alternative embodiment, device100 further includes a monitor, not shown, but configured to display oneor more of: dipole density information; potentials recorded byelectrodes 316; and cardiac chamber contours and other geometryinformation. In a preferred embodiment, dipole density and or recordedpotentials information is shown in reference to a three-dimensionalrepresentation of the heart chamber into which catheter 310 is inserted.In an alternative embodiment, imaging unit 220 may include a deviceconfigured to create an image of the cardiac chamber from signalsrecorded from an electrode catheter, such as catheter 310.

System 500 may include a device for treating a cardiac arrhythmia, suchas ablation source 230, which is electrically attached to electrodes 316via cable 318. Alternatively or additionally, ablation source 230 can beattached to a different ablation catheter, such as a single or multipleablation element catheter configured to deliver ablation energy such asRF energy, cryogenic energy, or other tissue disrupting energy.

System 500 may further comprise ultrasound unit 240, which is operablyconnected to ultrasound sensor, crystal 340 via cable 319. Unit 240includes ultrasound transducer 341, an operably attachable clampingassembly configured to be placed around the shaft of a catheter deviceand cause one or more components of the catheter device to transmitultrasound waves, such as waves configured to reflect off one or morestructures and be recorded by crystal 340. Unit 240 processes themeasurement data obtained by crystal 340 (i.e. the reflections recordedby crystal 340) and forwards the data to device 100. Measurement datamay include the position of crystal 340 relative to the cardiac chamberand the electrodes 316, as has been described in detail in reference toFIG. 1 hereabove.

As shown in FIG. 3, triangle T1, defined by device 100 is at location Y.Electrode 316 a of catheter 310 is at location X. The geometricrelationship between triangle T1 and Location X is defined by the solidangle, angle {acute over (ω)}(X,Y). Device 100 includes dipole densitymodule 130, as shown in FIG. 1, such that each triangle at location ycontributes {acute over (ω)}(x,y) times the dipole density d(y) to thepotential V(x) at the position x on a multi-electrode. Solid angle{acute over (ω)}(x,y), as defined above, corresponds to the triangle ata location y and the electrode at positions x on the multi-electrodearray. The dipole density module 130, as shown in FIG. 1, of device 100determines from the total measured potential V(x), which is the sumresulting from all the triangles defined by device 100, the desireddipole density d(y).

When sufficient potentials values V(x) are measured (e.g. from 10 to10,000 with increasing number of measured potentials providing moreaccurate results), the dipole density d(y) at many equally distributedregions y on the cardiac wall is calculated by solving a linear equationsystem. By interpolation of the measured potentials (e.g. with help ofsplines) their number can be increased to a higher number of regions.The solid angle {acute over (ω)}(x,y) of a region is the sum of thesolid angles of the individual triangles in the region on the cardiacwall. This calculation of dipole density results, such as via anautomatic computer program forming at least part of dipole densitymodule 130, as shown in FIG. 1.

In a preferred embodiment, the results are presented in a visual,anatomical format, such as depicting the dipole densities on a geometricimage of the cardiac wall in relation to time (t). This format allows aclinician, such as an electrophysiologist, to determine the activationsequence, or other electrical and mechanical measures, on the cardiacwall, such as to determine treatment locations for a cardiac arrhythmiaor other inadequacy in cardiac tissue health, such as force of tissuecontraction and motion of the chamber wall. The results may be shown ona display of mapping unit 210, or on a separate unit such as a displayincluded with device 100, display not shown but preferably a colormonitor. In a preferred embodiment, the device of the present inventionis implemented as, or includes, a software program that is executable byat least one processor. The software program can be integrated into oneor more of: an ECG system; a cardiac tissue ablation system; an imagingsystem; a computer; and combinations of these.

In a preferred embodiment, the multi-electrode catheter includes atleast ten electrodes, configured to represent a three dimensional bodywith known geometry. The electrodes are preferably positioned in aspherical geometry, such as a spherical geometry created in a basketcatheter, comprising support arms 314. Elliptical electrode arraygeometries may be used, such as those provided in the Ensite ArrayCatheter, manufactured by St. Jude Medical of St. Paul Minn. In analternative embodiment, multiple catheters are inserted into the heartchamber to provide the multiple electrodes.

In an alternative embodiment, the electrodes of the multi-electrodemapping array are repositioned during the method of determining dipoledensities. Repositioning of electrodes can be beneficial to increase thenumber of measured potential values, if electrode positions are known.Therefore, repositioning is in concordance with adjustment of thegeometry map in relation to the multi-electrode mapping catheter.

Referring now to FIG. 4, a side view of a catheter comprising anultrasound sensor configured to determine real-time continuousmeasurements of the position of the catheter within a cardiac chamber isillustrated. Catheter 310 comprises shaft 311 and array 315 positionedon the distal end of shaft 311. Array 315 comprises multiple supportarms 314 which include one or more electrodes 316 and one or moresensors, ultrasound crystal 340. Each crystal 340 may be positioned onelectrode 316, on a support arm of array 315, or at another catheter 310location. In a preferred embodiment, crystal 340 is located between twoelectrodes 316 as shown, or in a center portion a single electrode 316.

Ultrasound crystal 340 is configured to detect ultrasound waves, such asultrasound waves produced by ultrasound emitter 341, preferably aremovable clamping assembly including emitter 341 and clamped to shaft311 of mapping catheter 310 as is described in detail in reference toFIG. 5 herebelow. Emitter 341 is configured to produce high frequencyvibrations, i.e. ultrasound waves in a pulsed or constant manner. One ormore sound emitting devices, such as devices configured to clamp to oneor more catheters, may be used to transmit sound to one or more crystals340. In one embodiment, a first clamping assembly with a particularultrasound frequency may be used with a first catheter, while a secondclamping assembly with a second ultrasound frequency may be used with asecond catheter. In another embodiment, ultrasound sensor 340 ispositioned on a second elongate shaft, not shown but configured to beinserted into mapping catheter 310, such as through one or more lumens,not shown, of mapping catheter 310. In a preferred embodiment, one ormore crystals 340 may be configured to both record and transmitultrasound waves, such as to avoid the need for emitter 341. Crystals340 and electrodes 316 may be provided in various ratios, such as aratio of two electrodes to one ultrasound crystal, such as when eachultrasound crystal 340 has an electrode 316 positioned at each end. Inanother embodiment, a ratio of five electrodes 316 to two crystals 340is provided, such as a catheter shaft including sets of two assemblieswith a single electrode 316 positioned in between. Each assemblyincludes an ultrasound crystal 340 with an electrode 316 positioned ateach end.

In an alternate embodiment, a drive shaft 320 is operably connected to arotation mechanism, not shown but configured to rotate shaft 320 causingone or more crystals 340 to rotate within electrode 316 or anotherportion of catheter 310. As described in reference to FIG. 1 hereabove,crystal 340 may rotate a full 360° or may rotate through an arc lessthan 360°. Alternatively, catheter 310 may comprise a plurality ofcrystals 340 arranged in an array, for example, a circumferential arraysurrounding shaft 311, one or more electrodes 316 and/or a support arm314 of array 315, such as a phased array of crystals configured toproduce a 360° ultrasound image, well known to those of skill in theart.

In another embodiment, ultrasound sensor 340 comprises a probe, notshown, but typically a probe removably attached to or inserted withincatheter 310. In an alternate embodiment, ultrasound sensor 340comprises a piezoelectric film, not shown but typically covering one ormore electrodes 316 within array 315. In yet another embodiment,ultrasound sensor 340 comprises a piezoelectric cable, not shown butoperably connected to one or more electrodes 316.

Referring now to FIG. 5, a side view of a system including a mappingcatheter comprising a sensor and an ablation catheter comprising atransducer is illustrated. System 500 comprises mapping catheter 310 andablation catheter 400. Mapping catheter 310 comprises shaft 311including array 315 on its distal end. Array 315 includes one or moreelectrodes 316 mounted to one or more arms 314, each electrodeconfigured to record cellular activity in tissue. Array 315 furtherincludes one or more ultrasound emitting crystals 340, each positionedbetween two electrodes 316. Crystals 340 may be configured to bothrecord and transmit ultrasound waves.

Ablation catheter 400 comprises shaft 401, having a proximal portionwith a proximal end and a distal portion with a distal end, and clampingassembly 410. Clamping assembly 410 is shown positioned on shaft 401proximate handle 402, i.e. the proximal portion of shaft 401, such as ata location 10 cm from the proximal end of shaft 401. Clamping assembly410 comprises ultrasound transducer 412 and clamping mechanism 411configured to removably attach clamping assembly 410 to shaft 401 ofcatheter 400. Additionally, ablation catheter 400 comprises multipleablation elements, electrodes 420, located on the distal end of shaft401 and configured to deliver ablation energy (e.g. RF energy) and alsoto receive the ultrasound vibrations produced by clamping assembly 410and ultrasound transducer 412. In turn, electrodes 420, and one or moreother components of ablation catheter 400, emit ultrasounds waves. Theemitted ultrasound waves are received by ultrasound crystals 340 ofcatheter 310, and can be used to produce position information relativeto one or more components of ablation catheter 400 and/or mappingcatheter 310. Clamping assembly 410 is configured to produce highfrequency vibrations, i.e. ultrasound waves in a pulsed or constantmanner, typically with a frequency between 5 and 18 MHz. In anotherembodiment, ablation catheter 400 may include a conduit, not shown buttypically a solid or hollow tube configured to transmit the ultrasoundwaves from the proximal portion to the distal portion of ablationcatheter 400.

In an alternate embodiment, one or more support arms, not shown, may beattached to ablation catheter 400 (e.g. similar to the support arms 314of array 315 of catheter 310), and electrodes 420 may be located on theone or more support arms. The support arms may be radially distributedabout ablation catheter 400 and may comprise various geometric shapes,e.g. circular or rectangular. In this embodiment, clamping assembly 410may be constructed and arranged to vibrate the one or more support arms,in turn vibrating the one or more electrodes, thus transmittingultrasound waves to sensors 340. In another embodiment, electrodes 420may be configured to record electrical activity in cells as well asdeliver ablation energy.

In one embodiment, catheter 400 may further include one or more sensors,not shown but typically including one or more sensors selected from thegroup consisting of: a temperature sensor, such as a thermocouple; apressure sensor; an acoustic sensor, such as an ultrasound crystal; anelectromagnetic sensor, such as an electrode configured to recordelectrical information produced by living cells; and combinations ofthese. Clamping assembly 410 may be constructed to transmit vibrationsto the one or more sensors such that ultrasound waves transmitted by theone or more sensors can be detected by crystals 340 of catheter 310and/or another sensor of the system, such that geometric and otherposition information can be determined and utilized by a clinician toperform a medical procedure.

Alternatively or additionally, catheter 400 may further include one ormore transducers, not shown but typically including one or moretransducers selected from the group consisting of: an ablation elementsuch as an energy delivering electrode, a cryogenic transducer, amicrowave transducer and/or a laser delivery element; a soundtransducer, such as an ultrasound crystal; a heating element; a coolingelement; a drug delivery device; and combinations of these. Clampingassembly 410 may be constructed to transmit vibrations to the one ormore transducers such that ultrasound waves transmitted by the one ormore transducers can be detected by crystals 340 of catheter 310 and/oranother sensor of the system, such that geometric and other positioninformation can be determined and utilized by a clinician to perform amedical procedure.

Clamping assembly 410 may be attached to any ablation catheter,eliminating the need for a customized catheter. As discussed hereabove,clamping assembly 410 is constructed and arranged to vibrate one or morecomponents of a catheter, such as a sensor or transducer of thecatheter, such that one or more sensors, typically ultrasound sensors,can identify the location of the sensors or transducers vibrated by theclamping assembly. In one embodiment, a first clamping assembly with aparticular ultrasound frequency may be used with a first ablationcatheter, while a second clamping assembly with a second ultrasoundfrequency may be used with the same ablation catheter. Alternatively oradditionally, electrodes 420 may include a piezo crystal or otherwise beconfigured to transmit ultrasound waves that can be received by crystals340 of catheter 310.

Referring now to FIG. 6, a flow chart of an embodiment of a method fordiagnosing the tissue of a patient is illustrated. In STEP 50, thedistal end of an electrode catheter is placed into one or more bodylocations, such as one or more cardiac chambers of a patient. Theelectrode catheter comprises at least one electrode and at least oneultrasound element. The electrode catheter includes one or moreelectrodes positioned on a distal portion of the catheter and configuredto record electrical activity in tissue and/or deliver ablation energy.In STEP 60, anatomical information, such as tissue location, tissuemovement, tissue thickness and/or tissue contour information may bedetermined via the at least one ultrasound element, typically an elementconfigured to transmit and receive ultrasound waves. Alternatively oradditionally, position and/or distance information can be recorded, suchas position and/or distance information relative to one or more devicecomponents and/or tissue locations. In STEP 70, the electrical charge ofone or more tissue locations may be determined via the at least oneelectrode. STEPs 60 and 70 may be performed simultaneously orsequentially, in full or partial steps, and in any order. Either or bothSTEPs 60 and 70 may be performed in two or more independent timeperiods. In STEP 80, an analysis of the ultrasound reflections recordedand the electrical charge information is performed. This analysisincludes producing a diagnosis and/or prognosis of the tissue portion.For example, electrical information indicative of adequate electricalactivity and anatomical information indicative of the adequacy of tissuemotion may correlate to presence of healthy tissue.

For example, electrical information indicative of adequate electricalactivity and anatomical information indicative of adequate tissue motioncorrelates to presence of healthy tissue. Additionally, electricalinformation indicative of adequate electrical activity and anatomicalinformation indicative of inadequate tissue motion correlates topresence of at least one of ischemic tissue or hibernating tissue.Conversely, electrical information indicative of inadequate electricalactivity and anatomical information indicative of inadequate tissuemotion correlates to presence of scar tissue. Additionally, electricalinformation indicative of inadequate electrical activity and anatomicalinformation indicative of inadequate tissue motion correlates topresence of a complete ablation, such as an ablation performed in acardiac ablation performed to treat a cardiac arrhythmia. In someembodiments, the complete ablation comprises a transmural ablation. Inthis use, the diagnosis and/or prognosis can include the confirmation ofthe creation of a transmural lesion in the patient's heart tissue, suchas when both tissue motion and electrical activity have been eliminatedor decreased below a threshold.

More specifically, the following four cases may exist:

-   -   Case 1: Electrical and anatomical are adequate—Tissue is        healthy,    -   Case 2: Electrical is adequate and anatomical is        inadequate—Tissue is compromised,    -   Case 3: Electrical is inadequate and anatomical is        adequate—Tissue is compromised, and    -   Case 4: Electrical and anatomical are both inadequate—Tissue        necrosis.

The actual threshold for determining adequacy of electrical function ofany one area of the heart is dependent upon many factors, including thedegree of coordination of the activation pattern and the mass of thecells being activated. Additionally, this threshold will be differentfor each chamber of the heart as well as from smaller to largerpatients. For example, a threshold of 0.5 mV may be appropriate, whereinan electrical potential smaller that 0.5 mV may be indicative ofinadequate electrical function and an electrical potential at or largerthan 0.5 mV may be indicative of adequate electrical function.

Also included in the tissue diagnostic, a clinician may assess theelectrical integrity of cardiac cells. For example, the functionalstatus of the cardiac cells may be assessed. In one embodiment, theelectrical information comprises dipole density information.Additionally or alternatively, the electrical information may compriseat least one of repolarization or speed of repolarization information.

The method may further comprise ablating the cardiac tissue based uponthe tissue diagnosis. For example, the anatomical information comprisingtissue thickness information and at least one of the magnitude ofablation energy or the time period in which ablation energy isdelivered, is adjusted based on the tissue thickness informationrecorded by one or more ultrasound sensors.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theembodiments disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims. In addition,where this application has listed the steps of a method or procedure ina specific order, it may be possible, or even expedient in certaincircumstances, to change the order in which some steps are performed,and it is intended that the particular steps of the method or procedureclaims set forth herebelow not be construed as being order-specificunless such order specificity is expressly stated in the claim.

1. A device for creating a database of dipole densities d(y) anddistance measurements at the surface of one or more cardiac chambers ofa patient, said device comprising: multiple electrodes located on one ormore catheters; a transducer constructed and arranged to emit soundwaves; and a sensor constructed and arranged to receive reflections ofthe sound waves. 2.-175. (canceled)
 176. The device of claim 1, whereinthe transducer comprises the sensor.
 177. The device of claim 1, whereinthe device is constructed and arranged to produce a real time image.178. The device of claim 1, wherein the device is constructed andarranged to produce continuous images.
 179. The device of claim 1,wherein the device is constructed and arranged to produce images of thepatient's tissue.
 180. The device of claim 179, wherein the imagecomprises an image of the one or more cardiac chambers.
 181. The deviceof claim 179, wherein the image comprises an image of at least one ofthe multiple electrodes.
 182. The device of claim 1, wherein the deviceis constructed and arranged to provide motion information of thepatient's tissue.
 183. The device of claim 1, wherein the device isconstructed and arranged to provide thickness information of thepatient's tissue.
 184. The device of claim 1, wherein the device isconstructed and arranged to produce a distance measurement comprisingthe distance between at least one of the multiple electrodes and a wallof a cardiac chamber.
 185. The device of claim 1, wherein the device isconstructed and arranged to provide tissue diagnostic information byanalyzing both tissue motion information and cell electrical signals.186. The device of claim 185, wherein the device is constructed andarranged to provide the tissue diagnostic information during a cardiacablation procedure.
 187. The device of claim 1, wherein the device isconstructed and arranged to provide the location of cardiac tissue withcomplex electrograms.
 188. The device of claim 1, further comprising adelivery sheath.
 189. The device of claim 1, wherein at least one of thesensor or the transducer comprises a single component.
 190. The deviceof claim 1, wherein at least one of the sensor or the transducercomprises an array of components.
 191. The device of claim 190, whereinthe array comprises an array of ultrasound crystals.
 192. The device ofclaim 1, wherein the device comprises a multiple arm assembly andwherein the at least one of the sensor or the transducer is mounted tothe multiple arm assembly.
 193. The device of claim 192, wherein a firstelectrode of the multiple electrodes is mounted to the multiple armassembly.
 194. The device of claim 1, wherein the transducer comprisesan ultrasound transducer.
 195. The device of claim 1, wherein thetransducer produces signals with a frequency between 3 Mhz and 18 Mhz.196. The device of claim 1, wherein the sensor comprises an ultrasoundsensor.
 197. The device of claim 1, wherein the sensor comprisesmultiple sensors.
 198. The device of claim 1, further comprising: afirst receiver constructed and arranged to receive mapping informationfrom the multiple electrodes, the mapping information received when themultiple electrodes are placed in the one or more cardiac chambers; adipole density module constructed and arranged to generate the threedimensional database of dipole densities d(y), wherein the dipoledensity module determines a dipole density for individual triangleshaped projections onto the cardiac chamber wall, where each triangleprojection at a location y contributes {acute over (ω)}(x,y) times thedipole density d(y) to a potential V(x) at a point x, wherein {acuteover (ω)}(x,y) is the solid angle for that triangle projection, andwhere: a) x represents a series of locations within one or more cardiacchambers; and b) V(x) is a measured potential at point x, said measuredpotential recorded by the multiple electrodes.
 199. The device of claim1, wherein the dipole density is determined for at least 1000 triangleshaped projections.
 200. The device of claim 1, wherein the dipoledensity module determines a map of dipole densities d(y) atcorresponding time intervals.
 201. The device of claim 1, wherein thedipole density module generates a synthesis of maps that represents acascade of activation sequences of each corresponding heart beat from aseries of heart beats.
 202. The device of claim 1, wherein the measuredpotentials V(x) are interpolated to increase the number of regions. 203.The device of claim 1, further comprising: a third receiver configuredto receive mapping information from one or more skin electrodes. 204.The device of claim 203, wherein the dipole density module uses saidmapping